Imaging device

ABSTRACT

An image pickup apparatus is able to shoot an image of a wide range by a plurality of image pickup units, it is able to obtain excellent image quality and it can be miniaturized. An image pickup apparatus  20  comprises a plurality of image pickup units  1  including an image pickup device  3  and a front lens  2 , the adjacent image pickup units  1  being located in such a manner that image pickup areas overlap each other and the image pickup units being located so as to satisfy a conditional equation AL&lt;fD (1) where a cross-section passing a viewpoint center, an image pickup device  3  and a front lens  2  is created in the direction in which the image areas of the adjacent image pickup portions overlap with each other, a cross-section length of the image pickup device  3  is assumed to be A, a cross-section length of the front lens  2  is assumed to be D, a length from the front lens  2  to the image pickup device  3  is assumed to be L and a focal length which results from synthesizing the whole of the lenses within the image pickup unit  1  containing the front lens  2  is assumed to be f and that the viewpoint center of each image pickup unit  1  may lie within a sphere with a diameter of 20 mm.

TECHNICAL FIELD

The present invention relates to an image pickup apparatus composed of aplurality of image pickup units including a lens and an image pickupdevice.

BACKGROUND ART

A large number of image pickup apparatus capable of shooting a pictureof a wide angle of view by using a plurality of cameras have beenproposed so far.

For example, there has been proposed an image pickup apparatus in whicha plurality of cameras is mounted on a polyhedron frame (see citedpatent reference 1, for example).

However, according to this arrangement, since viewpoint centers of therespective cameras are not coincident with each other, parallax(parallax) is produced between the cameras so that a plurality of imagescannot be joined with high quality. Also, when it is intended to take apicture of an object near (within the shortest range) the camera, it isunavoidable that the dead angle at which the camera is unable to take apicture is produced.

On the other hand, there has been proposed an image pickup apparatus inwhich viewpoint centers of a plurality of cameras can be madesubstantially coincident with each other imaginarily by a pyramidalmirror (see cited patent references 2 and 3, for example)

Cited Patent Reference 1: Official Gazette of Japanese laid-open patentapplication No. 2001-203924 (FIG. 5)

Cited Patent Reference 2: Official Gazette of Japanese published patentapplication No. 39-8140 (FIG. 1)

Cited Patent Reference 3: Official Gazette of Japanese laid-open patentapplication No. 8-307735 (FIG. 1)

In the arrangement using the pyramidal mirror, since the viewpointcenters of a plurality of cameras are optically coincident with eachother, those problems of the parallax and the dead angle relative to theobject within the shortest range do not arise.

However, since the above-mentioned arrangement needs the pyramidalmirror, problems arise in which the whole of an image pickup apparatusbecomes large in size and in which the mirror must be prevented frombeing cracked or smudged, causing it to be difficult to handle thepyramidal mirror.

Further, since it is not possible to take a picture in the directionalong the central axis of the pyramid (in the upper and lower directionin the ordinary location of the pyramidal mirror) due to the structureof the pyramidal mirror, it is difficult to take pictures in alldirections.

In order to solve the above-mentioned problem, it is an object of thepresent invention to provide an image pickup apparatus capable ofshooting a picture in a wide range by a plurality of image pickup unitswhich can obtain excellent image quality and which can be miniaturized.

DISCLOSURE OF THE INVENTION

An image pickup apparatus according to the present invention comprisinga plurality of image pickup units including an image pickup device and afront lens, the adjacent image pickup units being located in such amanner that image pickup areas of the image pickup units may overlapeach other, is characterized in that the image pickup units are locatedin such a manner that a conditional equation:AL<fD  (1)is satisfied where a point at which a principal ray at the end of anangle of view is extended to cross an optical axis at each image pickupunit is defined as a viewpoint center, a cross-section passing theviewpoint center, the image pickup device and the front lens is createdin the direction in which the adjacent image pickup units and the imagepickup areas overlap each other, a cross-section length of the imagepickup device is assumed to be A in the cross-section, a cross-sectionlength of the front lens is assumed to be D, a length from the frontlens to the image pickup device is assumed to be L and a focal lengthwhich results from synthesizing the whole of lenses within the imagepickup unit containing the front lens is assumed to be f; and that theviewpoint centers of a plurality of image pickup units lie within asphere with a diameter of 20 mm.

Also, in the above-mentioned image pickup apparatus, the adjacent imagepickup units and the image pickup areas overlap each other in aplurality of directions and the image pickup units satisfy theconditional equation (1) in all of a plurality of directions.

According to the above-mentioned arrangement of the image pickupapparatus of the present invention, when a point at which a principalray at the end of an angle of view is extended to cross an optical axisat each image pickup unit is defined as a viewpoint center, across-section passing the viewpoint center, the image pickup device andthe front lens is created in the direction in which the adjacent imagepickup units and the image pickup areas overlap each other, across-section length of the image pickup device is assumed to be A inthe cross-section, a cross-section length of the front lens is assumedto be D, a length from the front lens to the image pickup device isassumed to be L and a focal length which results from synthesizing thewhole of lenses within the image pickup unit containing the front lensis assumed to be f, the conditional equation AL<fD is satisfied.

At that time, an angle of view of lens W and a visual angle θ from theimage pickup device to the lens in the direction in which the adjacentimage pickup units and the image pickup areas overlap each other areexpressed by the following equations (2) and (3):W=2 tan⁻¹(A/(2f))  (2)θ=2 tan⁻¹(D/(2L))  (3).

Then, since an inequality of AL<fD of the conditional equation (I) issatisfied, an inequality of 0<A/(2f)<D/(2L) is established and afunction f(x)=2 tan⁻¹x is monotonically increased with respect to x.Thus, an inequality of W<θ is satisfied.

As a result, since the visual angle θ from the image pickup device tothe lens is larger than the angle of view of lens W, the viewpointcenter is located behind the image pickup device. Thus, it becomespossible to make other image pickup units and the viewpoint centersbecome substantially coincident with each other.

Then, since the image pickup units are located in such a manner that therespective viewpoint centers of a plurality of image pickup units maylie within the sphere with the diameter of 20 mm, it becomes possible tooverlap images obtained from these image pickup units with each otherwithout causing parallax.

Also, in the above-described image pickup apparatus, when the adjacentimage pickup units and the image pickup areas overlap each other in aplurality of directions and the image pickup units satisfy theconditional equation (1) in all of a plurality of directions, it becomespossible to overlap images with each other without causing parallax.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic construction diagram (cross-sectional view alongthe horizontal direction) of an image pickup apparatus according to anembodiment of the present invention;

FIG. 2 is a cross-sectional view of one image pickup unit of the imagepickup apparatus shown in FIG. 1; and

FIG. 3 is a schematic construction diagram (perspective view) of animage pickup apparatus according to another embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a schematic construction diagram (cross-sectional view alongthe horizontal direction) showing an image pickup apparatus according toan embodiment of the present invention.

This image pickup apparatus 20 is constructed in such a manner that 12(1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L) image pickup units(cameras) 1 including a front lens 2 and an image pickup device 3 arelocated in a radial fashion and that the adjacent image pickup units 1are joined together.

In each image pickup unit 1, the front lens 2 is located at its frontend and the image pickup device 3 is located near its rear end. Eachimage pickup unit includes a lens group 4 between the front lens 2 andthe image pickup device 3.

According to this arrangement, the respective image pickup units 1A to1L share image pickup areas of 30 degrees each to provide an imagepickup area of 360 degrees in total.

In order that images obtained from the adjacent image pickup units 1 mayoverlap each other and in order that a mechanical error may be absorbed,it is preferable that the angle of view W in the horizontal direction ofeach image pickup unit 1 should be selected to be slightly larger than30 degrees so that the image pickup areas of the adjacent image pickupunits 1 may overlap each other.

Further, although not shown, the image pickup areas of the respectiveimage pickup units 1A to 1L have angles of view of 30 degrees each andhence the image pickup apparatus 20 is able to shoot a cylindricalpanoramic image on the whole.

The viewpoint centers of the respective image pickup units (cameras) 1are substantially coincident with each other at a central point 10 ofthe image pickup apparatus 20. In each image pickup unit 1, theviewpoint center is defined as a point at which a principal ray at theend of the angle of view is extended to cross the optical axis.

Next, FIG. 2 is a cross-sectional view showing one image pickup unit(camera) 1 of the image pickup apparatus 20 in detail.

The outsides of the respective assemblies (front lens 2, lens group 4and image pickup device 3) of the image pickup unit 1 are covered with acamera lens-barrel 5, and this camera lens-barrel 5 is formed so as toextend along rays at substantially the end of the angle of view.

The image pickup device 3 is shaped like a flat surface of a squareshape although not shown.

The image pickup apparatus 20 according to this embodiment may have anarrangement in which the respective image pickup units 1 (1A to 1L), inparticular, can satisfy the aforementioned conditional equation (1).That is, in the horizontal direction in which the image pickup areas ofthe adjacent image pickup units 1 may overlap each other, an inequalityof AL<fD in the conditional equation (1) should be satisfied where:

A: cross-section length of horizontal direction of image pickup device 3(=length of one side)

f: focal length of lens (whole focal length of front lens 2 and lensgroup 4)

D: cross-section length of horizontal direction of front lens 2

L: length from front lens 2 to image pickup device 3.

In this embodiment, since the image pickup device 3 is shaped like theflat surface of the square shape, it is customary that the image pickupdevice 3 is located in such a manner that the respective sides of thesquare may become corresponding to the horizontal directions and theupper and lower directions. Thus, the cross-section length of thehorizontal direction of the image pickup device 3 coincides with thelength of one side of the image pickup device 3. If the image pickupdevice is located in such a manner that the diagonal lines of the squaremay become corresponding to the horizontal direction and the upper andlower direction, then the cross-section length of the horizontaldirection of the image pickup device 3 coincides with the length of thediagonal line of the image pickup device 3.

As a result, with respect to the angle of view of lens W and the visualangle θ from the image pickup device 3 to the front lens 2, theinequality of W<θ is established based on the conditional equation (1)and the following equations (2) and (3):W=2 tan⁻¹(A/(2f))  (2)θ=2 tan⁻¹(D/(2L))  (3).

As described above, since the visual angle θ from the image pickupdevice 3 to the front lens 2 is larger than the angle of view of lens W,the viewpoint center is located behind the image pickup device 3. Thus,it becomes possible to make the viewpoint centers of the respectiveimage pickup units 1 (1A to 1L) become nearly coincident with one point10 shown in FIG. 1.

The following design conditions of the image pickup apparatus 20according to this embodiment are possible, in which the length A of oneside of the image pickup device 3 is equal to 3.6 mm, the diameter D ofthe front lens 2 is equal to 38.6 mm, the length L from the front lens 2to the image pickup device 3 is equal to 58.7 mm and the focal length fof the lens is equal to 6.5 mm.

At that time, since AL=3.6×58.7=211.32 and fD=6.5×38.6=250.9, theinequality of AL<fD is established and hence the conditional equation(1) can be satisfied.

Then, since W=2×tan⁻¹(3.6/2/6.5)=30.96 and θ=2×tan⁻¹(38.6/2/58.7)=36.4are established from the equations (2) and (3), an inequality of W<0 isestablished and it is to be understood that the viewpoint center islocated behind the image pickup device 3.

On the other hand, as a comparative arrangement, let us consider thecase which cannot satisfy the conditional equation (1).

If the length A of one side of the image pickup device 3 is equal to 3.6mm, the diameter D of the front lens 2 is equal to 30 mm, the length Lfrom the front lens 2 to the image pickup device 3 is equal to 58.7 mmand the focal length f of the lens is equal to 6.5 mm, that is, thediameter D of the front lens 2 is reduced to 30 mm, then AL=211.32 andfD=6.5×30=195. Thus, an inequality of AL>fD is established and hence theconditional equation (1) cannot be satisfied.

In this case, since W=2×tan⁻¹(3.6/2/6.5)=30.96 andθ=2×tan⁻¹(30/2/58.7)=28.7 are established from the equations (2) and(3), an inequality of θ<W is established. Also, since the length P fromthe front lens to the viewpoint center=D/2/ tan(W/2)=54.2 mm isestablished, an inequality of P<L is established.

Accordingly, since the inequalities of θ<W and P<L are established, theviewpoint center is located within the lens lens-barrel so that itbecomes difficult to make the viewpoint centers of a plurality of imagepickup units become close to each other.

According to the above-mentioned arrangement of the image pickupapparatus 20 of this embodiment, since the respective image pickup units1 can satisfy the conditional equation (1), the viewpoint center can belocated behind the image pickup device.

As a consequence, without using a mirror, the respective viewpointcenters of a plurality of image pickup units (cameras) 1 (1A to 1L) canbe located so as to lie within the sphere with the diameter of 20 mm,more preferably, the respective viewpoint centers can be substantiallymade coincident with each other.

As described above, since the viewpoint centers are located so as to liewithin the sphere with the diameter of 20 mm or they are madesubstantially coincident with each other, no parallax occurs so thatimages at the joints need not be processed when images shot by therespective image pickup units 1 are joined.

As a consequence, image quality can be maintained to be high and aprocessing time for joining images can be omitted or reduced.

Accordingly, processing for overlapping images can be executed in areal-time fashion and it is possible to apply the present invention to alive broadcast and the like with ease.

Then, since the image pickup apparatus 20 according to this embodimentdoes not use a mirror, a cameraman is not troubled by a mirror which isdifficult to handle and hence the image pickup apparatus according tothe present invention can be made easy to handle similarly to theordinary lens. In addition, as compared with the case in which the imagepickup apparatus uses a mirror, the image pickup apparatus 20 can beminiaturized.

Also, when a cameraman intends to take a picture of an object in theshortest range from the image pickup apparatus 20 according to thisembodiment, the dead angle is not produced and hence the image pickupapparatus according to the present invention can take pictures of anyobjects.

Further, when the image pickup apparatus 20 according to this embodimentis compared with other arrangements of an image pickup apparatus fortaking pictures in all directions, for example, an arrangement using afisheye lens and a single camera or an arrangement using a curvedsurface mirror and a single camera, it is possible to maintain much morepicture elements, since the image pickup areas can be overlapped witheach other by using a plurality of image pickup units 1 (1A to 1L).

Since much more picture elements can be maintained as described above,it becomes possible to improve resolution and also it becomes possibleto improve image quality.

Also, since the image pickup area of one image pickup unit 1 is narrowedand a range in which lenses (front lens 2 and lens group 4) for use withthe image pickup unit 1 are selected can be widened so that it becomespossible to use a lens having high optical performance, it becomespossible to obtain sufficient resolution and image quality bymaintaining, in particular, resolution near the joint of the imagepickup areas of the respective image pickup units 1.

Accordingly, it is possible to shoot pictures of high image quality inthe whole circumference of the belt-like area.

While the viewpoint centers of the respective image pickup units 1 aremade substantially coincident with one point 10 in the above-mentionedembodiment, a slight difference can be allowed insofar as such slightdifference does not bother the connection of the images and the presentinvention is not limited to the arrangement in which the viewpointcenters are made substantially coincident with one point.

Then, in order to prevent the joint of the images from being disturbed,it is desired that the viewpoint centers of the respective image pickupunits 1 should be located so as to lie within the sphere with thediameter of 20 mm.

Also, while the optical assemblies (front lens 2, lens group 4 and imagepickup device 3) of the respective image pickup units 1 have the samearrangement and the respective image pickup units 1 have the samearrangement shown in FIG. 2 in the above-mentioned embodiment, even whenthe arrangements of the respective image pickup units 1 are differentfrom each other, if the respective arrangements of the image pickupunits can satisfy the conditional equation (1), then, since theviewpoint center can be located behind the image pickup device, theviewpoint centers can be located within the sphere with the diameter of20 mm so that the images can be joined without trouble.

While the image pickup apparatus 20 according to this embodimentincludes 12 cameras (image pickup units) 1 arrayed in one row so thatthe belt-like range of 360 degrees in the horizontal direction and thebelt-like range of 30 degrees in the vertical direction can be providedas image pickup areas, in order to widen the shooting range in thevertical direction, it is sufficient that a plurality of camera rows inwhich cameras (image pickup units) are arrayed in a belt-like fashion inthe horizontal direction may be accumulated in the vertical direction,for example.

As a result, it becomes possible to shoot images of every direction (alldirections) containing the upper and lower direction.

An embodiment of this case will be described next.

Subsequently, FIG. 3 is a schematic construction diagram (perspectiveview) of an image pickup apparatus according to another embodiment ofthe present invention.

As shown in FIG. 3, 6 camera rows R1 to R6, in total, of a first camerarow R1 composed of cameras (image pickup units) C11, C12, C13, . . . , asecond camera row R2 composed of cameras (image pickup units) C21, C22,C23, C24, C25, . . . , a third camera row R3 composed of cameras (imagepickup units) C31, C32, C33, C34, C35, . . . , a fourth camera row R4composed of cameras (image pickup units) C41, C42, C43, C44, C45, . . ., a fifth camera row R5 composed of cameras (image pickup units) C51,C52, C53, C54, . . . , and a sixth camera row R6 composed of cameras(image pickup units) C61, C62, C63 . . . , are accumulated to constitutea spherical image pickup apparatus 100.

Also, in this image pickup apparatus 100, another camera C71 may befurther provided at the polar portion of the sphere. Another camera maybe provided at the polar portion of the opposite side of the sphere,although not shown.

Then, in the respective camera rows R1, R2, R3, R4, R5 and R6, theviewpoint centers of several cameras (image pickup units) comprising thecamera row may be located within the sphere with the diameter of atleast 20 mm, more preferably, those viewpoint centers should be madesubstantially coincident with each other. The viewpoint centers of therespective cameras (image pickup units) are defined similarly to theaforementioned embodiment.

The respective cameras should be located in such a manner that all ofthe viewpoint centers of the cameras (image pickup units) of therespective camera rows R1, R2, R3, R4, R5 and R6 may be located near thecenter of the sphere of the image pickup apparatus 100 rather than nearthe centers of the belt-like camera rows R1, R2, R3, R4, R5 and R6 inorder to join images of the upper and lower camera rows withoutparallax.

More preferably, the viewpoint centers of all cameras (image pickupunits) should be made substantially coincident with the center of thesphere of the image pickup apparatus 100.

While D assumed the cross-section length of the horizontal direction ofthe front lens 2 and A assumes the cross-section length (length of oneside) of the horizontal direction of the image pickup device 3 in thepreceding embodiment, according to the present invention, the respectiveimage pickup areas of the adjacent image pickup units may overlap eachother in a certain direction, and D and A may be defined as thecross-section lengths in such direction.

Accordingly, in the image pickup apparatus 100 according to thisembodiment, since the respective image pickup areas of the adjacentimage pickup units within the same camera row overlap each other, when Dassumes a cross-section length Dx of the horizontal direction of thefront lens and A assumes a cross-section length (length of side ofhorizontal direction) Ax of the horizontal direction of the image pickupdevice, the image pickup apparatus is constructed in such a manner thatthese cross-section lengths may satisfy the conditional equation (1).

That is, the image pickup apparatus is constructed so as to satisfy thefollowing equation (1X):AxL<fDx  (1X).

Further, in order to overlap the image pickup areas of the image pickupunits of the camera rows accumulated in the upper and lower direction,that is, the image pickup areas of the upper and lower image pickupunits each other, further, when D assumes a cross-section length Dy ofthe upper and lower direction of the front lens and A assumes across-section length (=length of side of upper and lower direction) Ayof the upper and lower direction of the image pickup device, the imagepickup apparatus is constructed in such a manner that thesecross-section lengths may satisfy the conditional equation (1).

That is, the image pickup apparatus is constructed so as to satisfy thefollowing equation (1Y):AyL<fDy  (1Y).

When the flat surface shape of the image pickup device is square, Ax=Ayis established.

The length L is constant regardless of the direction.

Astigmatism may be prevented from being produced by using a lens(spherical lens, etc.) whose focal length f becomes constant regardlessof the direction as the front lens or the intermediate lens group.

According to the above-mentioned image pickup apparatus 100 of thisembodiment, since the image pickup apparatus is constructed so as tosatisfy the conditional equation (1) in the direction in which thecameras (image pickup units) may overlap each other, the viewpointcenters of the respective cameras (image pickup units) are locatedbehind the image pickup devices so that it becomes possible to locatethe viewpoint centers of several cameras of respective camera rows orthe viewpoint centers of all cameras within the sphere with the diameterof 20 mm, more preferably, it becomes possible to make the viewpointcenters become substantially coincident with each other.

As a result, similarly to the image pickup apparatus 20 according to thepreceding embodiment, no parallax occurs so that images at the jointsneed not be processed when images shot by the respective image pickupunits 1 are joined and image quality can be maintained to be high. Also,a processing time for joining images can be omitted or reduced.

Accordingly, processing for overlapping images can be executed in areal-time fashion and it is possible to apply the present invention to alive broadcast and the like with ease.

Then, since the image pickup apparatus 100 according to this embodimentdoes not use a mirror, a cameraman is not troubled by a mirror which isdifficult to handle, and hence, the image pickup apparatus according tothe present invention can be made easy to handle similarly to anordinary lens. In addition, as compared with the case in which the imagepickup apparatus uses a mirror, the image pickup apparatus 100 can beminiaturized.

Also, when a cameraman intends to take a picture of an object in theshortest range from the image pickup apparatus 100 according to thisembodiment, the dead angle is not produced and hence the image pickupapparatus according to the present invention can take pictures of anyobjects.

Further, when the image pickup apparatus 100 according to thisembodiment is compared with another arrangement of an image pickupapparatus for taking pictures in all directions, for example, anarrangement using a fisheye lens and a single camera or an arrangementusing a curved surface mirror and a single camera, it is possible tomaintain much more picture elements, since the image pickup areas can beoverlapped with each other by using a plurality of image pickup unitsC11 to C71.

Since much more picture elements can be maintained as described above,it becomes possible to improve resolution and also it becomes possibleto improve image quality.

Also, since the image pickup area of one image pickup unit 1 is narrowedand a range in which lenses for use with the image pickup unit areselected can be widened so that it becomes possible to use a lens havinghigh optical performance, it becomes possible to obtain sufficientresolution and image quality by maintaining resolution near the joint ofthe image pickup areas of the respective image pickup units.

Accordingly, it is possible to shoot pictures of high image quality inall directions.

Further, according to the image pickup apparatus 100 of this embodiment,since 6 rows of the camera rows R1, R2, R3, R4, R5 and R6 in whichseveral cameras (image pickup units) are arrayed in a belt-like fashionare accumulated, it becomes possible to take pictures in all directionscontaining upper and lower directions at the same time.

While a plurality of image pickup units is disposed around the centralaxis of the image pickup apparatus 20 and 100 in a radial fashion andthis central axis is extended in the vertical direction in theabove-mentioned respective embodiments, the present invention is notlimited thereto and this central axis may be extended in the horizontaldirection and other directions.

Further, while a plurality of image pickup units can take pictures of360 degrees of the belt-like area, that is, pictures of the wholecircumference in the above-mentioned respective embodiments, the presentinvention is not limited thereto and a plurality of image pickup unitsmay take pictures of a part (for example, 120 degrees, 180 degrees, 240degrees and the like) of the whole circumference.

Also, the shape of the image pickup area of each image pickup unit isnot limited to a substantially quadrangular shape and other shapes suchas a hexagonal shape and a pentagonal shape like a soccer ball are alsopossible.

Regardless of the shape of the image pickup area of each image pickupunit, in the respective directions of the direction (one direction or aplurality of directions) in which the image pickup areas of the adjacentimage pickup units overlap each other, the cross-section length A of theimage pickup device and the front lens D obtained when the cross-sectionpassing the viewpoint center, the image pickup device and the front lensis created may satisfy the conditional equation (1).

The present invention is not limited to the above-mentioned embodimentsand can take various arrangements without departing from the gist of thepresent invention.

According to the above-mentioned image pickup apparatus of the presentinvention, no parallax occurs so that images at the joints need not beprocessed when images shot by the respective image pickup units 1 arejoined and image quality can be maintained to be high. Also, aprocessing time for joining images can be omitted or reduced.

Accordingly, processing for overlapping images can be executed in areal-time fashion and it is possible to apply the present invention to alive broadcast and the like with ease.

Also, since the image pickup apparatus according to the presentinvention does not use a mirror, a cameraman is not troubled by a mirrorwhich is difficult to handle and hence the image pickup apparatusaccording to the present invention can be made easy to handle similarlyto the ordinary lens. In addition, the image pickup apparatus can beminiaturized.

Further, when a cameraman intends to take a picture of an object in theshortest range, the dead angle is not produced and hence the imagepickup apparatus according to the present invention can take pictures ofany objects.

Further, according to the image pickup apparatus of the presentinvention, since images of a plurality of image pickup units can bejoined and much more picture elements can be maintained, it becomespossible to improve resolution and image quality.

Also, since the image pickup area of one image pickup unit is narrowedand a range in which lenses for use with the image pickup unit areselected can be widened so that it becomes possible to use a lens havinghigh optical performance, it becomes possible to obtain sufficientresolution and image quality by maintaining resolution near the joint ofthe image pickup areas of the respective image pickup units.

Accordingly, it is possible to shoot pictures of high image quality in awide range such as a whole circumference or all directions.

1. An image pickup apparatus capable of shooting a picture in a widerange comprising a plurality of adjacent image pickup units, wherein thefields of view of adjacent image pickup units within the image pickupapparatus overlap each other; wherein each image pickup unit comprises:a front lens; a lens group; and an image pickup device; wherein the lensgroup is positioned between the front lens and the image pickup device;wherein, within each image pickup unit, if a point at which a principalray at an end of an angle of view is extended to cross an optical axisis defined as a viewpoint center, the front lens, the lens group, andthe image pickup device are arranged such that the viewpoint center islocated behind the image pickup device; wherein, if a cross-section ofthe image pickup unit extends down an optical axis of the image pickupunit, each of the image pickup units satisfy a conditional equationAL<fD, where: A is a cross-sectional length of the image pickup devicewithin the cross-section; L is a cross-sectional length from the frontlens to the image pickup device within the cross-section; f is a wholefocal length of a lens system comprising the front lens and the lensgroup; and D is a cross-sectional length of the front lens within thecross-section; and wherein the viewpoint centers of the plurality ofimage pickup units lie within a sphere with a diameter of 20 mm.
 2. Animage pickup apparatus according to claim 1, wherein the fields of viewof adjacent image pickup units within the image pickup apparatus overlapeach other in a plurality of directions and the image pickup unitssatisfy the conditional equation in all of the plurality of directions.3. An image pickup apparatus according to claim 1, wherein a first frontlens of a first image pickup unit and a second front lens of a secondimage pickup unit adjacent to the first image pickup unit are shapedfollowing a cross-section passing through the viewpoint center and aprinciple ray at the end of an angle of view.